hw/sd: Introduce sd_cmd_handler type

Add 2 command handler arrays in SDProto, for CMD and ACMD.
Have sd_normal_command() / sd_app_command() use these arrays:
if an command handler is registered, call it, otherwise fall
back to current code base.

Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Message-Id: <20210624142209.1193073-5-f4bug@amsat.org>
Signed-off-by: Cédric Le Goater <clg@kaod.org>

hw/sd/sd.c

@@ -87,8 +87,12 @@ enum SDCardStates {
     sd_disconnect_state,
 };
 
+typedef sd_rsp_type_t (*sd_cmd_handler)(SDState *sd, SDRequest req);
+
 typedef struct SDProto {
     const char *name;
+    sd_cmd_handler cmd[SDMMC_CMD_MAX];
+    sd_cmd_handler acmd[SDMMC_CMD_MAX];
 } SDProto;
 
 struct SDState {
@@ -1031,6 +1035,10 @@ static sd_rsp_type_t sd_normal_command(SDState *sd, SDRequest req)
         return sd_illegal;
     }
 
+    if (sd_proto(sd)->cmd[req.cmd]) {
+        return sd_proto(sd)->cmd[req.cmd](sd, req);
+    }
+
     switch (req.cmd) {
     /* Basic commands (Class 0 and Class 1) */
     case 0:  /* CMD0:   GO_IDLE_STATE */
@@ -1575,6 +1583,11 @@ static sd_rsp_type_t sd_app_command(SDState *sd,
     trace_sdcard_app_command(sd_proto(sd)->name, sd_acmd_name(req.cmd),
                              req.cmd, req.arg, sd_state_name(sd->state));
     sd->card_status |= APP_CMD;
+
+    if (sd_proto(sd)->acmd[req.cmd]) {
+        return sd_proto(sd)->acmd[req.cmd](sd, req);
+    }
+
     switch (req.cmd) {
     case 6:  /* ACMD6:  SET_BUS_WIDTH */
         if (sd->spi) {